I can vouch for use of Pyright as LSP for neovim and helix. Very useful, especially the strict mode.
I usually pair it with pyre, another great tool
Could you comment on why you use both pyright and pure?
FB people have great experience with introducing typing into weakly typed languages (e.g. PHP vs Hack). So I actually started using pyre-check in place of mypy. The tool is really great and fast. I also like pysa quite a lot.
Pyright only came into focus because it was best Python LSP implementation for NeoVim, and it is also the default for helix-editor which I play with. It's also nice that I could suggest pyright for some younger colleagues using VisualStudio Code (with strict mode enabled of course).
P.S. I'm also using other interesting tools and libraries from FB (Instagram) like libcst [1] or fixit [2]
[1] https://github.com/Instagram/LibCST/ [2] https://github.com/Instagram/Fixit